Obviously it wasn't, the guy was innocent.
Suggestive evidence, yes. Worthy of a SWAT team entry and verbally abusing the man, HELL NO!
No, obviously it was. A internet connection that he pays for every month was used to download child porn. That's about as "solid" as it gets. See my comment about a car you own at a fatality accident.
The only person he has to blame here is himself.
BTW, do I think that forced entry in a case of suspected child pornography is appropriate? You BET! - It's far from a victimless crime, in fact it's one of the single most heinous crimes imaginable, and it's a crime that can be covered up with literally a mouse click or key stroke. Surprise is the only advantage they have.
This is NOT a case of the cops showing up without cause or at the wrong address. They were at the RIGHT address with clearly established probable cause.